Many individuals incorrectly assume that because a patient's chest pain is relieved with nitroglycerine, the pain is more likely to be cardiac in nature. In examining this question, Henrikson and colleagues [39] found a higher incidence of relief of chest pain in patients without ACS than those with active ischemia. Steele and colleagues [40] also found that nitroglycerine relieved chest pain in 66% of patients who were ultimately diagnosed with noncardiac chest pain. This data shows that chest-pain relief by nitroglycerine had no value in predicting or disproving ACS. Similarly, physicians have used the GI cocktail (a mixture of antacids and viscous lidocaine) to prove the likelihood of a GI cause and disprove the presence of ACS. There is no recent literature supporting the use of the GI cocktail for differentiating these types of pain, but the practice persists. Many physicians believe that burning substernal pain relieved by antacids is clearly caused by esophagitis or gastritis. Subsequent studies have actually shown that “burning” chest pain or pain described as “indigestion” may be as strong a descriptor of ischemia as chest pressure. [28],[31] In a small descriptive study, Wrenn and colleagues [41] found indiscriminate use of the GI cocktail for various ED complaints. In this subset, a significant portion of patients who were subsequently admitted with possible myocardial ischemia reported total or partial relief after administration of a GI cocktail.

In summary, chest-pain relief with either nitroglycerine or GI cocktail does nothing to improve the diagnostic accuracy for ACS and should not be used to influence decision making. (emphasis mine)

Relief of symptoms with nitroglycerin is not helpful in distinguishing ACS from GERD. Unfortunately, most ED patients with GERD-like symptoms therefore also have anginal-like symptoms, and most will need an ACS workup. It's not that the ACS workup relieves GERD symptoms; rather, in the ED we don't diagnosis patients. We "risk-stratify" (particularly with potential ACS) and determine which life-threatening diagnoses are potentially present, and whether the chance of that life threat is worth is sufficient to warrant workup (or treatment).